The present invention relates to an omnidirectional visual angle system for observing the circumjacent environment in all directions of 360xc2x0 and a retainer for the system.
In recent years, in the field of a visual angle sensor such as a monitor camera, there have been put into practice various trials to combine a camera with a computer so as to make the combination execute the work, which has conventionally been performed by a human being by his or her own sight. The camera, which is generally used in such a case, has a limited angle of visibility, and there are carried out trials to expand the angle of visibility by means of a wide-angle lens (fish-eye lens). Meanwhile, in the field of a mobile robot, there have been energetically conducted researches on utilizing a mirror having a surface of revolution (conic mirror, spherical mirror and so on) in order to expand the angle of visibility. These trials are to pick up a circumjacent optical image at an angle of visibility of 360xc2x0 by means of a mirror having a surface of revolution, convert this image into a video image and subject the resulting image to a process of conversion into the desired image by means of a computer.
FIG. 8 schematically shows the retainer of a conventional omnidirectional visual angle system that employs a mirror having a surface of revolution. In FIG. 8 are shown an optical system 1 constructed of a mirror having a surface of revolution, a video pickup means 2 for converting an optical image from the mirror having a surface of revolution into a video image and a transparent support 3 for connecting and supporting the optical system 1 with the video pickup means 2 by means of a screw 4. The optical image obtained by the optical system 1 using the mirror having a surface of revolution such as a conic mirror or a spherical mirror is converted into a video signal by the video pickup means 2 and then transmitted to a signal processing means (not shown) of the subsequent stage by a cable 5.
In this case, the mirror having a surface of revolution of the optical system 1 and the video pickup means 2 are connected and supported by the transparent support 3. The reason that the connection and support is performed by the transparent support 3 is to prevent the optical image of the support itself from entering the pickup image. It is to be noted that the retainer of the optical system 1 and the video pickup means 2 in the omnidirectional visual angle system are indispensable in order to improve the picture quality while preventing the entry of moisture and dust from outside.
However, the retainer of the aforementioned conventional omnidirectional visual angle system has the problems as follows. That is, the retainer of the aforementioned conventional omnidirectional visual angle system prevents the entry of moisture and dust from outside, whereas it is not particularly intended to have a waterproof structure.
Therefore, if it is tried to use the omnidirectional visual angle system outdoors, then it is required to take additional waterproof measures. Then, in such a case, there are waterproof measures for enclosing the entire omnidirectional visual angle system including the mirror having a surface of revolution (optical system 1) and the video pickup means 2 within another protective device.
However, if the system is enclosed within another protective device as described above, then there is the problem that the entire system becomes bulky and the protection structure becomes double, disadvantageously attenuating the quantity of received light of the optical system 1 by comparison with the case where only the transparent support 3 exists. When waterproof measures are taken by sealing up a space between the video pickup means 2 and the transparent support 3 with resin or the like, then there is much trouble in dismounting the video pickup means 2 and in replacing a component such as a solid-state image pickup device located inside the video pickup means.
Accordingly, the present invention has the object of providing an omnidirectional visual angle system, which is compact without any double protective structure, easy to replace components, free of visual field interruption and provided with sufficient waterproof measures as well as a retainer for the system.
In order to achieve the above object, there is provided an omnidirectional visual angle system having an optical system, which includes a mirror having a surface of revolution for obtaining an omnidirectional image in a visual field region, and an image pickup device for picking up the image obtained by the optical system, comprising:
a retainer, which retains therein the optical system and the image pickup device and has a waterproof structure and whose side surface has at least partially omnidirectional transparency.
According to the above construction, there is provided the retainer, which internally integrally retains the optical system including the mirror having a surface of revolution and the image pickup device and has the waterproof structure. Therefore, the retainment structure of the optical system and the image pickup device and the exterior casing for sealing use are integrated with each other without any double structure, and this enables the compacting of the system and restrains the reduction in quantity of reception light of the optical system. Furthermore, the side surface of the retainer has at least partially omnidirectional transparency, and therefore, the omnidirectional visual field region is not interrupted.
In one embodiment of the present invention, the retainer is comprised of a top section, a body section and a bottom section,
a portion that belongs to the body section and is located at least within a sight range of the mirror having a surface of revolution is transparent, and
a portion connecting the top section with the body section and a portion connecting the body section with the bottom section have a waterproof function and a detachable connection structure.
According to the above construction, the retainer is constructed of the top section, the body section and the bottom section, and each connecting portion has the waterproof function and the detachable connection structure. Therefore, the retainer can easily be separated into the portions, facilitating the replacement and the like of the components such as the mirror having a surface of revolution and the image pickup device. Further, the portion that belongs to the body section and is located within the sight range of the mirror having a surface of revolution is transparent. Therefore, the sight range of the mirror having a surface of revolution is not interrupted.
In one embodiment of the present invention, the body section has a cylindrical shape and includes a fixture portion of the mirror having a surface of revolution at an end of the top section, and
the bottom section is assembled with a mounting base for movably mounting the image pickup device along a center axis of the body section and with a fixture for fixing the image pickup device to the mounting base.
According to the above construction, the image pickup device is movably mounted on the bottom section along the center axis by means of the mounting base and the fixture. Therefore, the image pickup device can be moved with respect to the bottom section, and the distance between the mirror having a surface of revolution and the image pickup device can easily be varied.
In one embodiment of the present invention, the body section has a cylindrical shape,
the top section is integrated with the mirror having a surface of revolution, and
the bottom section is assembled with a mounting base for movably mounting the image pickup device along a center axis of the body section and with a fixture for fixing the image pickup device to the mounting base.
According to the above construction, the image pickup device can be moved with respect to the bottom section, and the distance between the mirror having a surface of revolution and the image pickup device can easily be varied. Furthermore, the mirror having a surface of revolution and the top section are integrated with each other. Therefore, the number of components to be assembled in the connection structure of the body section and the top section is reduced, allowing the separation and assembling to be simply performed.
In one embodiment of the present invention, the mirror having a surface of revolution has an outer peripheral edge to be brought in contact with an inner peripheral surface of the body section that has the cylindrical shape,
the fixture has a cylindrical shape and an outer peripheral surface to be brought in contact with an inner peripheral surface of the body section that has the cylindrical shape, and
optical axes of the mirror having a surface of revolution and the image pickup device coincide with each other.
According to the above construction, the optical axes of the mirror having a surface of revolution and the image pickup device coincide with each other, by which the omnidirectional visual angle system constituted by the mirror having a surface of revolution and the image pickup device brings its functions into full play.
In one embodiment of the present invention, the mirror having a surface of revolution is a hyperboloid mirror.
According to the above construction, the image in the omnidirectional visual field region can be easily securely picked up by the image pickup device.
Also, there is provided an omnidirectional visual angle system retainer, which is separated into a top section, a body section and a bottom section and in which a portion connecting the top section with the body section and a portion connecting the body section with the bottom section have a waterproof function and a detachable connection structure,
the body section having at least partially omnidirectional transparency,
the bottom section having a mounting base provided with a through hole that extends along a center axis of the body section, and
an image pickup device being able to be movably mounted along the center axis on the mounting base of the bottom section by means of the fixture by utilizing the through hole.
According to the above construction, the body section partially has omnidirectional transparency, and therefore, the omnidirectional visual field region is not interrupted. Furthermore, by virtue of the arrangement separable into the top section, the body section and the bottom section, the replacement and the like of the components such as the image pickup device are facilitated. In addition, the image pickup device can be movably mounted on the bottom section. Therefore, the distance between the mirror having a surface of revolution to be mounted on the top section or the end of the body section and the image pickup device is made variable.